The present invention relates to storage devices for digital appliances, and in particular to storage devices that are connectable through the Universal Serial Bus (USB) protocol.
Flash memories are used to store digital content in a variety of digital appliances, such as digital cameras, portable music players, digital voice recorders, handheld computers and cellular telephones. In some cases, a flash memory is permanently fixed within the appliance, and in other cases a flash memory module is removable from the appliance.
Many digital appliances interface with a personal computer (PC) to exchange data. One may wish to upload picture files from his digital camera, download music files to his portable music player, or synchronize the address book between his PC and his handheld computer or cellular telephone. When the data is stored in a removable memory module, users are often offered the choice between connecting the appliance to their PC via a cradle, cable or wireless interface in order to communicate with the memory module, or removing the memory module from the appliance and connecting it to the PC through an appropriate connector or adapter.
Flash memory modules are characterized by proprietary form factors and interfaces to operate with compatible appliances. Flash memory modules marketed under commercial names such as Smart Media, Compact Flash, Secure Digital, Multimedia Card or Memory Stick, feature different form factors and electrical interfaces, and manufacturers of commercial appliances select a specific type of flash memory module for interfacing with each appliance. On the other hand, the common PC data interfaces, such as serial or parallel ports, universal serial bus (USB) or Firewire, are incompatible with the interfaces commonly used by the appliances and memory modules, and therefore special adapters are required for connecting a memory module to a PC.
Reference is now made to FIG. 1, a simplified system drawing of background art. When a digital appliance 110 accommodating a permanent or removable memory module 102 is connected to a personal computer PC 121, appliance 110 usually has two interfaces—one interface with PC 121 ,e.g. USB device interface 115 and the second interface with memory module 102, e.g. Compact Flash (CF) 113—and a protocol converter 114 in order to channel data between the two incompatible interfaces 115 and 113.
Digital appliance 110, such as a digital camera, MP3 music player, voice recorder, handheld computer or cellular telephone, is controlled by processor 112 to operate the appliance's functions module 111. Functions module 111 include all the components, controls and software for executing the appliance-related functionalities such as taking pictures, replaying music, recording voice, etc. CompactFlash host interface 113 (or an alternative proprietary interface such as SmartMedia, MemoryStick, SecureDigital etc.,) is included in digital appliance 110 for exchanging data with memory module 102 via link 141. Universal Serial Bus (USB) device interface 115 is used for connecting appliance 110 and PC 121 through dumb cable 142. The purpose for connecting PC 121 to digital appliance 110 is actually for the PC to exchange data with memory module 102, using cable 142 to interface, e.g USB device 115 and link 141 to interface 113 (e.g. CF host interface); since the protocol, and possibly also the electrical characteristics of interface 115 and interface 113, are different, converter 114 is required to enable the data exchange between PC 121 and memory module 102. Converter 114 can be a standalone component, or form part of processor 112.
Memory module 102 includes CompactFlash device interface 105, flash storage 103, and controller 104 which manages read/write operations related to storage 103. When memory module 102 is inserted into digital appliance 110, memory module 102 exchanges data with processor 112 via compactFlash device interface 105, link 141 and CompactFlash host interface 113. Still inserted in digital appliance 110, memory module 102 can exchange data with PC 121 via link 141, CompactFlash device interface 113, converter 114, USB device interface 115, link 142, and USB host interface 124. Alternatively, memory module 102 can be removed from digital appliance 110 and inserted into reader/adapter 130, to communicate with PC 121 through CompactFlash device interface 105, link 144, CompactFlash host interface 131, converter 134, USB device interface 135, link 143, and USB host interface 124.
Reader/adapter 130 is a peripheral device of PC 121 to receive memory module 102. A variety of such devices for receiving CompactFlash, SmartMedia, SecureDigital, MultimediaCard and/or MemoryStick cards are available in the market. Reader/adapter 130 is connected to PC 121 via cable 143 through USB interfaces 124 and 135, and uses converter 134 to enable data exchange with memory module 102 through card interfaces 105 and 131 via contact link 144.
PC 121 is a general-purpose personal computer, that may upload and/or download data onto/from memory module 102 in cooperation with well-known applications of appliance 110 such as music player, digital camera or cellular telephone.
To facilitate the connection between flash memory module 102 and PC 121, some vendors have introduced a dual-interface memory module illustrated in FIG. 2 (background art). For example, Lexar Media, Inc. markets a Compact Flash memory card that includes a complete Compact Flash interface 154 that operates when the device is inserted into a compatible appliance, and a USB interface 153 that requires just a dumb cable in order to connect to and exchange data with PC 121, after being removed from a digital appliance.
The use of dual interfaces in appliance 110 and in some memory modules, i.e. module 150, as well as the need for protocol conversion at the appliance, all add to the complexity and cost of the current digital appliances and removable flash memory modules.
There is thus a need and it would be advantageous to have a storage device which communicates directly with both the appliance and an external host device, using a single communication protocol and without protocol converters or external readers.